Biomonitoring Of Metal Pollution Research Articles

Tilapia as a model fish for biomonitoring of metal pollution in dams associated with mining watersheds: contrasting diagnosis from different tissues and health risk assessment.

Tilapia is a model fish species used as a pollution biomonitor due to its tolerance and availability in many contaminated sites. Blue tilapia Oreochromis aureus specimens (n = 320) were collected in eleven dams influenced by mining in the SE Gulf of California region (dams 1, 2 and, 3 comprise 55 mining sites; dam 4 comprises 8; dams 6, 8, 10, and 11, ≤ 6; and dams 5, 7, and 9 include 19, 20, and 16 mining sites, respectively). Cadmium, Cu, Pb, and Zn concentrations were analyzed in the muscle, liver, gills, and guts to identify metal pollution and evaluate risks and seasonal changes. The distinct tissues exhibited different metal accumulation capacities, therefore allowed develop a diagnosis comparative between the eleven dams. In general, metal concentrations were higher in dams 1, 2, 5, and 9, which are associated with more mining sites in their sub-basins. The four metals exhibited the highest levels in the tilapia liver in dams 1 and 2, which can be related to the present and past mining activity in the lower watershed (55 sites) and the geothermal activity in these dams. In general, Zn exhibited the highest level in the tilapia livers from dams 1, 2, 3, 4, 5, and 10 compared to the maximum mean (220µg/g) concentrations previously recorded. The non-carcinogenic risks indicated that the Pb risk was enhanced when the intake was ≥ 231.5gweek-1 of tilapia muscle, indicating a potential risk of adverse health effects for the entire population.

Bioaccumulation of Metals in Some Auchenorrhyncha (Insecta: Hemiptera) Species in Cherry Orchards Near Motorway and Their Usage as Biomonitor for Metal Pollution.

Traffic borne pollutants negatively affect organisms. This study aimed to determine the impact of traffic pollution on Auchenorrhyncha species and their usage as biomonitor for metal pollution. The study was carried out in the cherry orchard near the Amasya-Samsun D100/E80 motorway in Amasya, Türkiye. Metal concentrations in specimens tended to decrease with the increasing distance from the motorway. Significant variations were determined in some metal concentrations based on distance from the motorway. The maximum and minimum metal concentrations were obtained from 0 to 100m, respectively. Negative relationships were determined between distance from the motorway and Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb concentrations in Arboridia versuta (Melichar, 1897), and Cd, Co, Cr, Cu, Ni and Pb concentrations in Psammotettix provincialis (Ribaut, 1925). Metals were accumulated in the body of specimens. Therefore, it is thought that Auchenorrhyncha species may be used as a biomonitor for metal pollution due to their high metal concentrations.

Pb intoxicated biomolecular changes in Cladonia convoluta studied using 2DCOS infrared spectroscopy coupled with chemometric analysis

Lead (Pb) is used in many industrial applications and is a toxic heavy metal that causes health hazards. Lichens are symbiotic associations that are environment friendly in removing toxic elements from the polluted environment. They can accumulate heavy metals and are therefore considered in biomonitoring of metal pollution. In this study, biochemical markers due to lead toxicity on Cladonia convoluta were revealed using two-dimensional correlation (2DCOS) spectra analysis. The 2DCOS enhances the resolution of the spectrum and gives more information on the interaction of functional groups within and between molecules which cannot be revealed from conventional spectra. Thus, 2DCOS is an efficient tool in monitoring even minute spectral changes in complex spectra. The results of conventional IR analysis showed changes in the band area. It follows in the order polysaccharides > proteins > lipids due to lead toxicity. The results of 2D correlation spectra show predominant changes at the pyranose ring. The hetero asynchronous map show correlation changes of pyranose ring with lipid and proteins. It reveals a change in carbohydrate synthesis due to toxicity. The highest positive and negative PCA loading values show deformation pyranose ring to glucan band. The results of HCA show samples are well separated into two major clusters with high separation values. ROC analysis gives good reliability of the test. Hence, 2DCOS coupled with chemometric analysis helps in understanding the biomolecular changes in C. convoluta effectively.

Shells of Intertidal Mudflat Snails: A Promising Biomonitoring Materials of Nickel Pollution

Monitoring the level of metal pollution in a water body, especially in polluted areas, is crucial. Gastropod shells have been used as a biomonitor for metal pollution. The goal of this study was to evaluate the utilisation of the mudflat snails, Telescopium telescopium shells, as biomonitoring materials for nickel (Ni) pollution in the intertidal area. The snails and their habitat surface sediments were sampled from 17 sites in Peninsular Malaysia. Up to 21 individuals from each site were sampled and dissected. In addition to the shells, six parts of the soft tissues (cephalic tentacle, foot, gill, muscle, mantle, and remaining soft tissues) were analysed for Ni. The snail shell was found to be a potential biomonitoring material for Ni pollution based on four positive points: (i) higher value of shell/soft tissue ratios (> 1.00); (ii) categorisation as a ‘microconcentrator’ based on bioaccumulation factor; (iii) significant correlation coefficients (at least P < 0.05) and significant influential total Ni levels in the sediments to the shell Ni; and (iv) higher precision of Ni in the shells based on the lowest value of the coefficient of variation of Ni. The described results indicated that the shell of T. telescopium would be suitable for assessing Ni pollution in the intertidal areas.

Bioconcentration of heavy metals by three plant species growing in Golmarz wetland, in northwestern Iran: The plants antioxidant responses to metal pollutions

In the present study heavy metal contaminations in water and sediments of the Golmarz wetland in northwestern Iran were determined. Moreover, bio-monitoring of metal pollution in the aquatic ecosystem and evaluating the role of some plant species in bioaccumulation and remediation of heavy metals from the environment were performed. The metal(loid) concentrations in water, sediment and plant samples were measured by inductively coupled plasma-mass spectroscopy (ICP-MS). It was established that there was no metal contamination in water samples, but the sediments were highly contaminated by Se and As. Typha latifoila was able to accumulate large amount of Cd, Pb, Ni, and Zn in its root and the amount of its enrichment coefficient of root for the elements was more than 1. Due to its large biomass and its high potential in elements uptake, T. latifolia was a suitable species for metal’s phytoremediation. Panicum maximum was capable to uptake and transporting Pb and Cd to its above-ground parts. Moreover, Scirpus lacustris showed good potential to accumulate of Cd and Pb in its root. The obtained results indicated that the activity of antioxidant enzymes and the amounts of phenol and flavonoids in three plant species were high in the most polluted sampling sites. Therefore, the plants try to adapt the existence of heavy metal by induction of their defense systems. • Determination of water and sediment pollution in Golmarz wetland. • Evaluation of phytoremediation potential of the indigenous plants. • Physiological responses of the plants in the polluted environment.

Macroalgae in biomonitoring of metal pollution in the Bay of Bengal coastal waters of Cox\u2019s Bazar and surrounding areas

Although coastal water marine algae have been popularly used by others as indicators of heavy metal pollution, data within the Bay of Bengal for the estuarine Cox’s Bazar region and Saint Martin’s Island has remained scarce. Using marine algae, the study herein forms an effort in biomonitoring of metal contamination in the aforementioned Bangladesh areas. A total of 10 seaweed species were collected, including edible varieties, analyzed for metal levels through the use of the technique of EDXRF. From greatest to least, measured mean metal concentrations in descending order have been found to be K > Fe > Zr > Br > Sr > Zn > Mn > Rb > Cu > As > Pb > Cr > Co. Potential toxic heavy metals such as Pb, As, and Cr appear at lower concentration values compared to that found for essential mineral elements. However, the presence of Pb in Sargassum oligocystum species has been observed to exceed the maximum international guidance level. Given that some of the algae species are cultivated for human consumption, the non-carcinogenic and carcinogenic indices were calculated, shown to be slightly lower than the maxima recommended by the international organizations. Overall, the present results are consistent with literature data suggesting that heavy metal macroalgae biomonitoring may be species-specific. To the best of our knowledge, this study represents the first comprehensive macroalgae biomonitoring study of metal contamination from the coastal waters of Cox’s Bazar and beyond.

Mediterranean fanworm, Sabella spallanzanii (Gmelin, 1791), as a potential biomonitor of trace metal pollution in the marine environment

Levels of trace metals (Cd, Cr, Cu, Fe, Ni, Pb, Mn, and Zn) were measured in soft tissues and external tubes of the Mediterranean fanworm, Sabella spallanzanii (Gmelin, 1791), to evaluate its suitability as a biomonitor of metal pollution. Study was conducted in the coastal area of the eastern Adriatic Sea. Polychaetes were collected from two locations, a site located in a local marina and an unpolluted control site. Results indicate that S. spallanzanii has the capacity to accumulate metals in soft tissues as well as in tubes. The levels of most metals were considerably higher in tubes compared to soft tissues, indicating long-term accumulation of metals in tubes. High levels of several metals (Cu, Zn, Cr, Pb and Fe), found in soft tissues and tubes sampled at the marina site, reflect the elevated contaminant levels in the marina, associated with the use of antifouling agents, paints, petrol additives, and ship maintenance activities. Metal concentrations in tissues and tubes generally decreased with size, indicating the influence of growth and metabolic rates on trace metal uptake. Trace metal levels found in S. spallanzanii tissues were comparable to the levels found in Mytilus galloprovincialis, a species commonly used in biomonitoring studies, in areas exposed to similar levels of anthropogenic stressors. According to the results of the present study, S. spallanzanii has been identified as a suitable biomonitor of metal pollution due to its sedentary nature, widespread distribution, abundance and the ability to accumulate high levels of metals within its tissues and tubes.

Use of Black Poplar Leaves for the Biomonitoring of Air Pollution in an Urban Agglomeration.

Trees are considered to be an effective tool for metal pollution biomonitoring. In the present study, the concentration of metals (Cu, Pb, Zn, Cd, Co, Ni, Fe, Mn, and Al) in black poplar leaves (Populus nigra L.), together with the concentration of PM10, PM2.5, PM1, and total suspended particles (TSP), was used for the air pollution biomonitoring in 12 sites from various areas of Cluj-Napoca city, Romania. The concentration of PM10 in the air was high, but their metal content was low. However, Cu, Pb, and Zn were moderately enriched, while Cd was highly enriched in PM10 due to anthropogenic sources. The average metal concentration in leaves decreased in the order Zn>>Fe>Mn>Al>Pb>Ni>Cu>Co>Cd and increased with the increase of PM10 concentration, indicating that poplar leaves are sensitive to air pollution. The principal component analysis indicated that traffic, waste burning, road dust resuspension, and soil contamination are the main anthropogenic sources of metals in poplar leaves. The results indicated that black poplar leaves are a suitable biomonitoring tool for metal pollution, in urban environments.

Tree species as a biomonitor of metal pollution in arid Mediterranean environments: case for arid southern Tunisia.

We investigated the accumulation of Zn, Cu, Pb, and Cd in the soil and the leaves and bark of five common tree species (Eucalyptus occidentalis Endl., Acacia salicina Lindl., Cupressus sempervirens L., Casuarina equisetifolia L., and Tamarix aphylla (L.) Karst.) in the city of Gabès Tunisia to elucidate their bioaccumulation potential and determine their usefulness as biomonitors of metallic pollution in arid urban areas. Our results indicated that the bark had higher mean concentrations of Pb and Cd than leaves. In contrast, the leaves had higher mean concentrations of Zn and Cu than bark. No hyperaccumulation was detected for any of the analyzed metals in any of the studied species. E. occidentalis and T. aphylla had the highest mean concentrations of the investigated metals in leaves and bark. Based on the calculated metal accumulation index (MAI) values, these two species accumulated more metals than other studied tree species. Likewise, the concentrations of Zn, Cu, Pb, and Cd in soil had significant positive correlations with that in leaves and bark. Accordingly, E. occidentalis could be used for biomonitoring in arid areas subjected to industrial and traffic pollution. T. aphylla would be a good alternative when native species are a priority.

Development and validation of in-situ and laboratory X-ray fluorescence (XRF) spectroscopy methods for moss biomonitoring of metal pollution

Metals are among the pollutants of highest concern in urban areas due to their persistence, bioavailability and toxicity. High concentrations of metals threaten aquatic ecosystem functioning and biodiversity, as well as human health. High-resolution estimates of pollutant sources are required to mitigate exposure to toxic compounds by identifying the specific locations and associated site characteristics where the deposition of metals is greatest. Mosses have been widely used as low-cost biological monitors of metal pollution for decades, because they readily accumulate pollutants over time, reflecting long term pollution levels. However, spectroscopic techniques to determine the concentration of metal pollutants in moss samples still require expensive instrumentation and involve time consuming sample preparation protocols with heavy use of reagents. Here we present protocols to perform in-situ and laboratory X-ray fluorescence (XRF) spectroscopy of epiphytic moss as rapid, low-cost, and accurate alternatives to conventional metal pollution biomonitoring. We also report on a preliminary validation of the measurements using mass fractions determined by inductively coupled plasma atomic emission spectroscopy (ICP-OES) as reference.•XRF measurements are taken from moss directly on tree trunks in less than five minutes.•Grinding and pelletizing of moss enables definitive quantitation (R2>0.90) of metals through portable XRF.

Trace element assessment in Neoechinorhynchus agilis (Rudolphi, 1918) (Acanthocephala: Neoechinorhynchidae) and its fish hosts, Mugil cephalus (Linnaeus, 1758) and Chelon ramada (Risso, 1827) from Ichkeul Lagoon, Tunisia.

Acanthocephalans belonging to the species Neoechinorhynchus agilis were collected from two mullets, Mugil cephalus and Chelon ramada from Ichkeul Lagoon in northern Tunisia. Collected parasites, as well as tissues of their hosts (muscle, liver and intestine), were analysed for trace elements (silver, arsenic, cadmium, cobalt, copper, iron, manganese, nickel (Ni), lead (Pb), selenium, vanadium (V), zinc) using inductively coupled plasma mass spectrometry. Our results showed different accumulation patterns of trace elements in fish tissues and parasites. Among the host tissues, liver accumulated the highest metal amounts. Acanthocephalans showed Ni, Pb and V in significantly higher concentrations compared to their host's tissues. Further, the calculated bioconcentration factors demonstrated a 390-fold higher Pb accumulation in the parasite compared to fish muscle. This study is the first field survey in Tunisia dealing with elements' uptake in parasites and their hosts. Our results corroborate the usefulness of the acanthocephalans for biomonitoring of metal pollution in aquatic ecosystems and promote more research in order to understand host-parasite systems in brackish waters of the Mediterranean area.

Green sea urchins (Strongylocentrotus droebachiensis) as potential biomonitors of metal pollution near a former lead-zinc mine in West Greenland.

In this study, metal accumulation in green sea urchins (Strongylocentrotus droebachiensis) was investigated near the former Black Angel lead-zinc mine in Maarmorilik, West Greenland. Sea urchins (n = 9-11; 31-59 mm in diameter) were collected from three stations located at < 1 km, 5 km, and 12 km (reference site) away from the former mine site, respectively. After collection, tissue of the sea urchins was divided into gonads and remaining soft parts (viscera) before subjected to chemical analyses. Focus was on eight elements found in elevated concentrations in the mine waste (iron, copper, zinc, arsenic, silver, cadmium, mercury and lead). Sea urchins at the mine site contained significantly more copper, mercury and lead compared with the reference site for both the gonads and viscera, while the latter also contained significantly more iron, zinc and silver. Arsenic and cadmium were not significantly elevated in sea urchins at the mine site. Most elements were found in higher concentrations in the viscera compared with the gonads. For comprehensive monitoring of metal pollution at mine sites, a diverse selection of monitoring organisms is necessary. The study shows that green sea urchins accumulate selected metals and can be used as a monitoring organism for mining pollution, at least for iron, copper, zinc, silver, mercury and lead. However, the results also show that green sea urchins are less likely to reflect small environmental changes in loading of most metals (except iron, copper and silver) and for arsenic compared to suspension feeders such as blue mussels.

Spiders as biomonitors of metal pollution at Arctic mine sites: The case of the Black Angel Pb-Zn-mine, Maarmorilik, West Greenland

Abstract Metal pollution from mining activities is a well-known environmental concern, and detailed environmental monitoring before, during, and after mining is essential to evaluate the contamination status of a mining area. We therefore investigated the use of Arctic wolf spiders as a potential monitoring organism for metal contamination. In the Arctic, spiders are the most abundant group of terrestrial predators, with documented abilities to accumulate metals. In Greenland however, most contamination studies in relation to mining have targeted the marine environment, with less attention given to the terrestrial. Following a distance transect (0–40 km) near the former Black Angel Pb-Zn-mine, Maarmorilik, West-Greenland, we collected samples of two species of wolf spiders (Pardosa glacialis and P. groenlandica), along with supporting samples from soil and lichens, and analyzed these for geochemical elements using Q-ICP-MS and DMA. We show that metal concentrations in spiders generally reflect the contamination trend of the area, i.e. decreasing concentrations with increasing distance from the old mine, but also that large differences in bioaccumulation efficiency occurs between elements (Ag > Cd > Zn > Cu > Hg > Pb). We also found larger differences between juvenile and adult (female) spiders than between species. Adults generally contained higher concentrations than juveniles, suggesting that distinguishing between age classes of spiders is critical in future assessments of the environmental contamination status using spiders as bioindicator- and biomonitoring organisms. Although further studies are needed, we conclude that, especially in the case of Ag and Cd, Arctic wolf spiders are show a promising biomonitor of metal contamination near Arctic mine sites and elsewhere.

Helix aspersa as sentinel of development damage for biomonitoring purpose: A validation study.

Environmental health has always been threatened by the bioaccumulation of heavy metals in the terrestrial ecosystem, affecting its quality and safety. The aim of this review is to investigate the effects of heavy metal soil contamination, using the land snail Helix aspersa as a bioindicator. H. aspersa, a common species of land snail present in the area, has been used as a bioindicator of metal contamination and represents a promising ecological indicator. Various land snails species have become popular in microcosm studies because they accumulate high concentrations of certain trace metals. They express contamination as a whole through ingestion of polluted foods, such as live plants, microorganisms, soil, and water and also through cutaneous contact and from the polluted air they breathe. Land snails are considered appropriate sentinel species because trace metals tend to accumulate in their digestive gland to allow biomonitoring of metal pollution. Different experiments demonstrate that exposure in areas chronically polluted with metals, especially with lead, often causes changes in reproduction, with a variation in the mineral composition in the snail's eggs and also in its development, due to increased energy expenses associated with detoxification and the excretion process.

Environmental Parasitology: intestinal helminth parasites of the siganid fish Siganus rivulatus as bioindicators for trace metal pollution in the Red Sea.

Studies on host-parasite systems as bioindicators for monitoring trace metal pollution in marine environments are still scarce. Here, 11, 14 and 17 infrapopulations of Gyliauchen volubilis (Trematoda: Digenea), Procamallanus elatensis (Nematoda) and Sclerocollum rubrimaris (Acanthocephala), respectively, were collected from the fish Siganus rivulatus (Siganidae) in the Red Sea, from a chronically polluted small bay at Sharm El-Sheikh, South Sinai, Egypt. Water and sediment samples from the bay, tissue samples (intestines, liver, and muscle) from each fish, and samples from each parasite were taken for heavy metal analyses of cadmium and lead. Cadmium concentrations in intestines, liver and muscle of non-infected and infected fishes were much lower than those of lead, and both metal concentrations decreased in the order: liver > intestines > muscle. Cadmium and lead concentrations in the tissues of fishes infected with G. volubilis or P. elatensis were slightly lower than those in non-infected ones, while in the tissues of fishes infected with Sc. rubrimaris, they were much lower. Low concentrations of cadmium and lead in G. volubilis and P. elatensis are associated with their limited ability or capacity to accumulate trace metals. Therefore, bioconcentration factors corresponding to these species were relatively low, and both are herein considered as weak bioindicators. By contrast, high concentrations of cadmium and lead in S. rubrimaris are associated with its high ability to accumulate trace metals. Of the present three host–parasite systems, only the Siganus rivulatus–Sclerocollum rubrimaris system seems to be promising for biomonitoring of metal pollution in the Red Sea.

Use of whole mussels and mussel gills in metal pollution biomonitoring

The use of marine bivalves in metal pollution monitoring is undoubtedly one of the best tools to evaluate metal pollution in coastal areas worldwide. However, since bivalves integrate metal pollution from both the dissolved and the particulate phases, it cannot be assured that metal bioaccumulation in their tissues will predict the risk posed by metals to sensitive organisms such as invertebrate larvae or microalgae, which are known to be mainly affected by the free metal ion fraction. This study aims to test the usefulness of mussel gills–the primary exchange surfaces with dissolved metals–in reflecting dissolved metal bioavailability in the field. For that, we analyzed metal concentrations in environmental samples (whole soft tissues of mussels, mussel gills, sediment, and particulate and dissolved fractions in the water column) collected from 7 sampling sites during a multi-year investigative monitoring survey in the Ría de Vigo. The results showed a different pattern of Cu and Zn accumulation in gills compared to whole soft tissues, and these differences are attributable to the faster response of gills to changes in dissolved metal concentrations and to the regulation of essential metals at the whole body level. In the case of Pb, by contrast, concentrations in gills were very similar to those in the whole body. The use of mussel gills in metal pollution biomonitoring is a promising tool for the detection of changes in bioavailable metals in the environment, especially for essential metals such as Cu and Zn.

Effects of dietary Pb and Cd and their combination on lysosomal and tissue-level biomarkers and histopathology in digestive gland of the land snail, Cantareus apertus (Born, 1778)

The present study was aimed at determining cell and tissue-level biomarkers and histopathological alterations in the green garden snail, Cantareus apertus (Born, 1778), exposed to different nominal dietary concentrations of Pb (25, 100 and 2500 mg Pb/kg), Cd (5, 10 and 100 mg Cd/kg) and their combination (25 mg Pb + 5 mg Cd/Kg, 100 mg Pb + 10 mg Cd/kg and 2500 mg Pb + 100 mg Cd/ kg) for 1 and 8 weeks. Lead and Cd exerted histopathological effects on the digestive gland in a dose-dependent manner and related to lysosomal and tissue-level biomarkers. The biological responses observed included digestive cell vacuolisation and numerical atrophy, calcium cell hydropic degeneration, excretory cell hypertrophy, inflammatory responses, blood vessel congestion, and disruption of the blood vessel wall and the interstitial connective tissue. Lysosomal enlargement and transient intracellular accumulation of neutral lipids and lipofuscins were also observed, together with alterations in the cell type composition and thinning of the digestive gland epithelium and with diverticular distortion. This response profile fits well with the biological effects reported after metal exposure in gastropods from other regions, as well as with data obtained in parallel studies dealing with metal bioaccumulation and intralysosomal accumulation, mortality, feeding, growth, oxidative stress and neurotoxicity exerted elicited by Pb, Cd and their mixture in green garden snails under the present experimental conditions. Consequently, C. apertus seems to be a suitable model species for the biomarker-based assessment of the biological effects of Pb and Cd, alone or in combinations, thus providing a challenging opportunity to advance in identifying suitable sentinel species for metal pollution biomonitoring and ecosystem health assessment in soil ecosystems in Northern Africa.

Sclerocollum saudii Al-Jahdali, 2010 (Acanthocephala: Cavisomidae) as a sentinel for heavy-metal pollution in the Red Sea.

Currently, fish helminth parasites, especially cestodes and acanthocephalans, are regarded as sentinel organisms to elucidate metal pollution in aquatic ecosystems. Here, 34 specimens of the fish Siganus rivulatus were collected in the Red Sea, from a seriously polluted, small lagoon named Sharm-Elmaya Bay, at Sharm El-Sheikh, South Sinai, Egypt; 22 (64.7%) were infected by Sclerocollum saudii (Acanthocephala: Cavisomidae). Thus, 22 natural infrapopulations (26-245 individuals) of this parasite were collected from infected fish. Samples of water and sediments from the bay, samples of muscle, intestine and liver from each fish, and samples from the parasite were taken for analysis of heavy metals (cadmium (Cd) and lead (Pb)). Both Cd and Pb concentrations in sediments were higher than those in water. The concentration of these metals were significantly higher in tissues (intestine, liver and muscle) of non-infected fish than those in infected fish, with Pb concentrations consistently higher than those of Cd, and both were drastically decreased in the order: liver &gt; intestine &gt; muscle. Metal concentrations in this acanthocephalan were much higher than those in its fish host. There were strong negative relationships between metal concentrations in tissues (intestine, liver and muscle) of infected fish and infrapopulation size, and between metal concentrations in the acanthocephalan and its infrapopulation size. These relationships strongly suggest competition for these metals between the fish host and its acanthocephalan parasite, and intraspecific competition among acanthocephalan individuals for available metals in the fish intestine. Bioconcentration factors were relatively high, since the mean Cd concentration in S. saudii was 239, 68 and 329 times higher than those in intestine, liver and muscle tissues, respectively, of its fish host. Also, mean Pb concentration was 55, 13 and 289 times higher than those in these tissues, respectively. The host-parasite system described here seems to be promising for biomonitoring of metal pollution in the Red Sea.

Green garden snail, Cantareus apertus, as biomonitor and sentinel for integrative metal pollution assessment in roadside soils.

The present investigation was conceived to study, in a small scale field study, the potential of the green garden snail, Cantareus apertus, as biomonitor and sentinel for integrative metal pollution assessment in soils. For this purpose, we investigated the association between the trace metal (Cd, Pb, As, Fe, Cr, Cu, Ni, and Zn) concentrations in soil, plants (Trifolium repens), and C. apertus depending on the distance (20, 150, and 700m) from a main roadside in Tunisia as well as between metal concentrations and biomarkers of oxidative stress, oxidative damage, and neurotoxicity in C. apertus. Results revealed a clear association between the concentration of metals such as Ni, Cu, and Zn in snail digestive gland, both amongst them and with oxidative stress and neurotoxicity biomarkers recorded in the same organ. Interestingly, Ni, Pb, and Zn occurred at the highest concentration in soil, plant, and snails and the association appeared related to the immediacy of the roadside and the concentration of these three metals tended to decrease with distance from the roadside in the soil-plant-snail system. Conversely, Cd and Cu were bioaccumulated in plants and snails but their concentrations in soil were not high and did not show a decline in concentration with distance from the roadside. After PCA analysis, PC-01 (56% of the variance) represented metal bioaccumulation and associated toxic effects in snails in the presence of high levels of metal pollution (nearby the roadside) while PC-02 (35% of the variance) represented stress induced by moderate levels of metal pollution (at intermediate distances from the roadside). The four studied sites were clearly discriminated one from each other, depending on how they are affected by traffic pollution. In summary, this field study reveals that (a) C. apertus can be used as biomonitor for metal pollution in roadside soils and as sentinel for pollution effects assessment based on biochemical biomarkers; and (b) that oxidative stress and neurotoxicity biomarkers endow with a powerful biological tool for metal pollution biomonitoring in soils, especially in combination with chemical analysis of the soil-plant-snail transfer system. Moreover, this study provides some baseline data for future impact assessments concerning trace metal pollution in Tunisia.

Mechanisms of cadmium accumulation (adsorption and absorption) by the freshwater bivalve Corbicula fluminea under hydrodynamic conditions

Many heavy metals in sediments and water have potential adverse effects on aquatic organisms such as Corbicula fluminea (O.F. Müller, 1774), a bivalve species frequently used as a biomonitor for metal pollution. Studies over the past decades examining the heavy metal uptake by C. fluminea, very few has investigated the effect of hydrodynamic conditions on accumulation of heavy metal by C. fluminea. Therefore, in this study, to investigate the mechanism of intracellular and extracellular accumulation of metal, individuals of C. fluminea were exposed to cadmium (Cd)-treated water under three different hydrodynamic conditions. These included exposures in two set ups: three rates of rotation (500, 350, 200 r/min) in beakers for 10 days, and then exposure to Cd-treated sediment under two naturally turbulent water conditions (14 cm/s and 3.2 cm/s) in experimental flumes for 23 days. Hydrodynamic force increased the burrowing rate but decreased the activity of C. fluminea. After 10 days of exposure, the extracellular concentrations of Cd in the tissues of C. fluminea in the sand group were significantly higher than that in the gravel groups. The intracellular and extracellular concentrations of Cd in the tissues of C. fluminea dramatically increased in the Cd-treated sediment test. Moreover, the concentration of the extracellular Cd adsorbed on the tissues of C. fluminea in the 14 cm/s and 3.2 cm/s groups was significantly higher than that in the control group, whereas the effect of hydrodynamic force on absorption of Cd by C. fluminea was not obvious. These results suggest that hydrodynamic condition plays an important role in extracellular accumulation of Cd by C. fluminea. In future study, when using C. fluminea to assess Cd pollution in aquatic environment, extracellular Cd adsorbed on the tissue should be removed to avoid the influence of hydrodynamics.